The present invention relates to a control device for an engine, particularly to a control device for an engine, which controls an engine torque according to operation of an accelerator pedal performed by a driver.
Conventionally, engines of vehicles are controlled in consideration of a jerk (a rate of change (derivative value) of an acceleration per unit time, also referred to as a jolt, surge, or lurch) which is produced in the vehicles. For example, JP5499882B2 discloses an art of controlling an engine torque to maximize a jerk of a vehicle when an actual torque reaches a predetermined ratio (e.g., between 70 and 80%) with respect to a target torque which is set based on an operation amount of an accelerator pedal of the vehicle. With this art, the actual torque is greatly increased to provide a driver of the vehicle with an acceleration feel corresponding to the operation state of the accelerator pedal.
Meanwhile, a swift increase of the jerk of the vehicle to a highest value when the accelerator pedal is depressed can provide the driver with a quick acceleration feel, in other words, the driver can be provided with an impression that the vehicle has a quick response. A point (timing) at which the jerk reaches a highest value tends to leave an impression on the driver, and the driver can predict a level of acceleration of the vehicle by depending on the impression regarding that point at which the jerk reaches the highest value. Based on this, it can be said to be preferable to swiftly increase the jerk of the vehicle to the highest value when the accelerator pedal is depressed.
On the other hand, if the highest value of the jerk of the vehicle is excessively high, the jerk of the vehicle cannot be kept at a suitable value and drops after reaching the highest value, and a linear acceleration feel can no longer be secured. Moreover, the excessively high highest value of the jerk of the vehicle causes an extension of the time period required for the jerk of the vehicle to reach the highest value. Therefore, it can be preferable to configure the vehicle so that a desired jerk is produced according to an accelerator opening, and the highest jerk is produced in the vehicle when the accelerator pedal reaches a suitable opening by being depressed.